The effect modification of the risk of suicide following self-harm by age and sex: a population-based nationally representative study from

ObjectiveTo Quantify the risk of suicide following self-harm within the various healthcare settings to which patients present to help understand the risk factors involved.MethodA matched case-control study using electronic records for primary care, secondary care (hospitals) and national mortality registries in England between 2001-2019 (N=594674). Cases with a death attributed to suicide were compared with a randomly selected control population.ResultsThe one-year suicide risk, adjusted for age and sex, was higher after recorded self-harm in primary care (odds ratio OR: 83, 95% confidence intervals CI: 76-91) and secondary care data (OR 124; 95% CI: 111-138) compared to those with no self-harm records. Suicide risk was highest in the first month after self-harm in primary care (OR 310; 95% CI: 244-393) and secondary care data (OR 458; 95% CI: 331-633). Suicide risk increased with the number of self-harm admissions in the final year (OR for patients with ≥3 self-harm attempts 505; 95% CI: 227-1123: p<0.0001 for trend). While suicide risk following self-harm was increased across all age-groups and sexes, it was higher in females and older individuals compared to their counterparts with no self-harm records (p<0.05). ConclusionIn both the primary care and secondary care datasets, the one-year relative suicide risk following self-harm was high, which is consistent with previous studies. The increased risk of suicide mortality following self-harm in older individuals and females may inform risk-stratification after a self-harm event.